1. Field of the Invention
This invention generally relates to a method and apparatus to resect the distal human femur to allow it to properly accept a distal femoral prosthesis.
2. Description of the Prior Art
Different methods and apparatus have been developed to enable a surgeon to resect the distal human femur to allow attachment of a distal femoral prosthesis (knee implant) to the human femur. Keeping in mind the ultimate goal of the procedure is to restore the knee joint to normal function, it is critical that the location and orientation of the knee implant approximates that of the natural knee.
It is common to use the central axis of the femur, the posterior and distal femoral condyles, and/or the anterior distal femoral cortex as guides to determine the location and orientation of distal femoral resections. The location and orientation of these resections are critical in that they dictate the final location and orientation of the distal femoral implant. It is commonly thought that the location and orientation of the distal femoral implant are critical factors in the success or failure of the artificial knee joint.
Past efforts have not been successful in consistently properly locating and orienting distal femoral resections. Such efforts are set forth in the following patents, none of which teach or suggest all of the benefits and advantages of the present invention. These previous patents include:
Stillwell, U.S. Pat. No. 4,457,307, which discloses a movable saw and saw carriage which may be mounted to a patient's femur and positioned to cut the femur bone. An elongated rail is secured substantially parallel to the femur. A saw carriage and a carriage housing are attached to the rail. The saw has a blade extending substantially parallel to the direction of linear movement of the saw carriage. The saw carriage is slidably guided along paths substantially parallel to the elongated rails for making cuts in the femur bone. The saw may be positioned in a plurality of second positions where the saw carriage is slidably guided in paths substantially perpendicular to the elongated rail for making traverse distal femur cuts and for scoring the tibia cortex. Additionally, the saw may be positioned in a plurality of third positions where the saw carriage is slidably guided to form an acute angle with the elongated rail for making anterior and posterior femur chamfer cuts.
Rohr, U.S. Pat. No. 4,566,448, discloses a ligament tensor device having a first member to engage the tibia and a second member to engage the intercondylar notch of a femur and a means for moving the second means with respect to the first means for applying a selected tension to the ligaments of the joint. Additionally, the invention includes cutting guide slots for guiding the cutting of the femoral condyles.
Keller, U.S. Pat. No. 4,586,496, discloses a surgical chisel having a flexurally rigid chisel shank and a thin, elongated chisel blade fixed at its front end. A chisel guide is provided having slides for displaceably guiding the blade and shank in a longitudinal direction.
Russell et al., U.S. Pat. No. 4,722,330, discloses a distal femoral surface shaping guide for mounting on an intramedullary alignment guide for use in shaping the distal femoral surface. A conventional shaping means such as an oscillating saw or hand saw is introduced through the guide surfaces to resection the femur. The device also includes stabilizing members with threaded, knurled cap bolts with points that extend along the sides of the femur to stabilize the device.
Zarnowski et al., U.S. Pat. No. 4,892,093, discloses a cutting guide for a saw blade for resecting a femur. The device is attached to a femur after the distal end has been removed and a transverse surface has been established. The cutting guide includes a base member having a planar base surface. A pair of laterally spaced-apart locating and securing posts are integral with the base member and project in a direction normal to the base surface to interconnect with the femur. Guide members in the form of cylindrical bars are positioned within side members attached to the base. A saw blade may be inserted between the guide surfaces to properly position the blade to cut the femur.
Vandewalls, U.S. Pat. No. 4,896,663, discloses a drill for drilling a hole into a femur. The device includes a positioning mechanism to firmly engage the outer peripheral surface of the femoral head and the femoral neck. This immobilizes the drill bushing relative to the femur and orients the axis of the drill with the central axis of the femur.
Schmidt, U.S. Pat. No. 5,049,149, discloses a sawing gauge system for intertrochantery accommodation osteotomies for removing a wedge-shaped section of bone with a predetermined wedge-angle so that an optimal pre-stress load F can act.
Lackey, U.S. Pat. No. 5,053,037, discloses a femoral drill guide with interchangeable femoral collets, a femoral reamer and a femoral anterior/posterior cutting block with an adoptable anterior femoral ledge. A plurality of diagonal slots are provided for making diagonal cuts in the distal end of the femur.
Ferrante et al. U.S. Pat. No. 5,098,436, discloses a modular guide for shaping a femur comprising a first bracket defining a generally U-shaped structure having an internal surface adapted to be seated on the distal aspect of a resected femur bone and an elongated central opening appointed to expose a selected area of the resected femur, including a curved track for guiding a first shaping tool along a predetermined path for controlled shaping of a curved patellar groove and a portion of the selected area exposed through the opening. A second bracket defines a linear slotted bore extending generally parallel to the long axis of the femur for guiding a second shaping tool to form a relatively deep recess accommodating an intercondylar-stabilizing housing of a knee implant.
Brown, U.S. Pat. No. 5,234,432, discloses a method of cutting the proximal end of a femur prior to cementing in a prosthesis for reconstructive hip surgery.
Additionally, Whiteside, U.S. Pat. No. 4,474,177 describes instruments for creating the distal femoral surfaces where a guide is used to index a flat surface used to guide the distal femoral resection. Kaufman, et al. U.S. Pat. No. 4,721,104 describes a method of preparing the intracondylar area of the distal femur. In addition, Kenna, U.S. Pat. No. 4,787,383 describes a saw and saw guide used to perform the most distal planar femoral resection. Jellicoe, U.S. Pat. No. 5,047,032 utilizes a side cutting drill to form the distal femoral surface.
None of these previous efforts, however, disclose all of the benefits and advantages of the present invention, nor do these previous patents teach or suggest all of the elements of the present invention.